Polyolefin fibers may be processed into many different articles, such as fabrics. Nonwoven fabrics made from staple fibers are useful in articles such as diapers, sanitary napkins, tampons, underpants, and the like. In some applications, such as diaper leg cuffs and waist bands, these fabrics are used to manage flow of liquids and it is desirable that the fibers be hydrophobic.
Polyolefin fibers and, in particular, polypropylene fibers, are naturally hydrophobic. Generally, when finishes containing antistatic compositions (also called antistats) and/or lubricants are applied to the fiber surface in order to spin, process and form the articles from fibers, the fibers are rendered hydrophilic in nature.
Schmalz, in U.S. Pat. No. 4,938,832 and European Patent Application No. 486,158 which are incorporated herein in their entirety by reference, teach fiber with finish compositions comprising at least one neutralized phosphoric acid ester having a lower alkyl group, such as a 1-8 carbon alkyl group, which functions as an antistat, in combination with a silicone lubricant. These fibers have excellent properties, particularly for manufacture of hydrophobic nonwoven fabrics for diapers. However, these antistats have been observed to quickly form solid deposits on cards and calender rolls when the fibers are formed into fabrics. That is, a white build-up of material visible to the naked eye forms on cards and calenders in less than two hours. This may require an operator to increase bonding temperature, slow down a line or clean equipment on a frequent basis.